SiBE28-804
Expansion Valve Regulating Functions
Functional Description
79
5.2
General Expansion Valve Control
Outline
After the start up control function has been terminated the general expansion valve control
function will regulate the expansion valve opening in function of the target suction SH value.
The discharge SH value will be used to set the target SH value.
The measured suction SH value will be used to control the opening of the expansion to the
target SH value.
Details
When the unit is in cooling or heating operation the opening of the expansion valve will be
controlled in order to keep the amount of superheat at the evaporator outlet constant. This way
the evaporator can be used at maximum efficiency under all conditions. The initial target heat
exchanger outlet superheat value = 5°C.
The target heat exchanger outlet superheat value can be increased in case the discharge
superheat value decreases.
The target heat exchanger outlet superheat value can be decreased in case the discharge
superheat value increases.
Control
During normal control 2 situations can decide on the expansion valve opening degree:
1. Target superheat amount:
When the target heat exchanger outlet superheat > actual heat exchanger
outlet superheat --> the expansion valve will close.
When the target heat exchanger outlet superheat < actual heat exchanger
outlet superheat --> the expansion valve will open.
The superheat amount is checked every 10 seconds.
2. Frequency change: At the time of compressor frequency change, the expansion valve
opening will be changed with a fixed value. This value will be in function of the amount of
compressor frequency change.
Calculations
RZQ71,
RZQS71·100
The heat exchanger outlet superheat value is calculated from the saturated suction temperature
Te(using LP sensor) and the suction pipe temperature R4T : SH = R4T-Te
The discharge superheat value is calculated from the saturated discharge temperature Td (HP
value calculated out of PI, frequency and LP) and the discharge pipe temperature R3T : SH =
R3T-Td
Calculations
RZQ100~140,
RZQS125·140
The heat exchanger outlet superheat value is calculated from the saturated suction temperature
Te(using indoor coil sensor in cooling, outdoor coil sensor in heating) and the suction pipe
temperature R4T : SH = R4T-Te
The discharge superheat value is calculated from the saturated discharge temperature Td (HP
value calculated out of PI, frequency and Te) or Tc and the discharge pipe temperature R3T :
SH = R3T-Td or R3T or SH = R3T-Tc (whichever is the lowest)
Summary of Contents for FHQ100BUV1B x 2
Page 13: ...SiBE28 804 2 ...
Page 19: ...Model Name and Power Supply SiBE28 804 8 General Information ...
Page 29: ...Specifications SiBE28 804 18 Specifications ...
Page 33: ...Wired Remote Controller SiBE28 804 22 Remote Controller 1 2 Installation ...
Page 34: ...SiBE28 804 Wired Remote Controller Remote Controller 23 ...
Page 93: ...Outdoor Unit Fan Speed Control SiBE28 804 82 Functional Description ...
Page 131: ...Test Run and Operation Data SiBE28 804 120 Test Operation ...
Page 251: ...Troubleshooting by Remote Controller Display LED Display SiBE28 804 240 Troubleshooting ...
Page 277: ...PCB Layout SiBE28 804 266 Appendix ...
Page 297: ...RZQ100 140C7 RZQS125 140C7V1B SiBE28 804 286 Removal Procedure ...
Page 311: ...SiBE28 804 iv Index ...